Merge pull request #2557 from topecongiro/vertical-layout-complex-attrs

[rust.git] / README.md

diff --git a/README.md b/README.md
index 69f4d800dfc841a77d3cf8e95e70ff0fdb3280e1..420859e90513df2a31060ae898c16d852bb56a11 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,7 +3,8 @@
 A tool for formatting Rust code according to style guidelines.
 
 If you'd like to help out (and you should, it's a fun project!), see
-[Contributing.md](Contributing.md).
+[Contributing.md](Contributing.md) and our [Code of
+Conduct](CODE_OF_CONDUCT.md).
 
 We are changing the default style used by rustfmt. There is an ongoing [RFC
 process][fmt rfcs]. The last version using the old style was 0.8.6. From 0.9
@@ -40,6 +41,36 @@ to run on a cargo project in the current working directory:
 cargo fmt
 ```
 
+
+## Limitations
+
+Rustfmt tries to work on as much Rust code as possible, sometimes, the code
+doesn't even need to compile! As we approach a 1.0 release we are also looking
+to limit areas of instability; in particular, post-1.0, the formatting of most
+code should not change as Rustfmt improves. However, there are some things that
+Rustfmt can't do or can't do well (and thus where formatting might change
+significantly, even post-1.0). We would like to reduce the list of limitations
+over time.
+
+The following list enumerates areas where Rustfmt does not work or where the
+stability guarantees do not apply (we don't make a distinction between the two
+because in the future Rustfmt might work on code where it currently does not):
+
+* a program where any part of the program does not parse (parsing is an early
+  stage of compilation and in Rust includes macro expansion).
+* Macro declarations and uses (current status: some macro declarations and uses
+  are formatted).
+* Comments, including any AST node with a comment 'inside' (Rustfmt does not
+  currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
+* Rust code in code blocks in comments.
+* Any fragment of a program (i.e., stability guarantees only apply to whole
+  programs, even where fragments of a program can be formatted today).
+* Code containing non-ascii unicode characters (we believe Rustfmt mostly works
+  here, but do not have the test coverage or experience to be 100% sure).
+* Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
+  fixes to break our stability guarantees).
+
+
 ## Installation
 
 ```
@@ -128,16 +159,14 @@ when a pull request contains unformatted code. Using `--write-mode=diff` instruc
 rustfmt to exit with an error code if the input is not formatted correctly.
 It will also print any found differences.
 
-A minimal Travis setup could look like this:
+A minimal Travis setup could look like this (requires Rust 1.24.0 or greater):
 
 ```yaml
 language: rust
 before_script:
-- rustup toolchain install nightly
-- rustup component add --toolchain nightly rustfmt-preview
-- which rustfmt || cargo install --force rustfmt-nightly
+- rustup component add rustfmt-preview
 script:
-- cargo +nightly fmt --all -- --write-mode=diff
+- cargo fmt --all -- --write-mode=diff
 - cargo build
 - cargo test
 ```